In recent years, the protection of confidential information has become an important issue in companies and the like, and techniques for preventing leakage of confidential information have been proposed. For example, Patent Literature 1 discloses a control technique in which, when copying a confidential document containing confidential information, an image of the confidential document is processed. Further, for example, Patent Literature 2 discloses a technique for allowing multiple portable terminals to download data selected by a portable terminal to which the host authority is given, and making all the portable terminals discard the data at the time of completion of presenting the data.